In Limit Hold'em poker, game play on the river is very different from the Flop and Turn. This is the last card to be dealt, which means there are no more draws and no more chances for you or your opponents to improve their hand. Nevertheless it's a very difficult street to play, and every wrong decision can cost you a lot of chips. You should therefore consider the following on the river:
Avoid folding the best hand
Most pots are fairly big on the river. This means that you often have good pot odds to call with only marginal hands. Say for instance the size of the pot after the turn is seven big bets. If your opponent bets on the river, you'll be getting pot odds of 8:1. This means you will have to win the pot at least once every nine times to make the call profitable. Folding the best hand therefore could cost you the whole pot, but calling with the weaker hand only costs one big bet. Don't forget however that you must also consider your opponents' playing style. A very tight player for example may bluff so rarely that calling a river bet usually won't be profitable.
Another important factor to consider is the betting pattern up to this point. How did your opponent act preflop, after the flop and then on the turn? With practice, you'll start to get a feel for the cards that the other players at the table might be holding - a skill that can make playing the river much easier.
The correct time to fold
Even with good pot odds, sometimes folding is the best option on the river. If you are unsure, you should consider the strength of your own hand, the playing style of your opponents, previous betting patterns and pot odds. If you feel you don't have the best hand after looking at all these factors, then folding on the river is the best option. Even if you still aren't sure, it can sometimes still be correct to call. If you lose the hand, its a mistake that has only cost you a small amount of chips.
Something else you need to think about is the number of players still in the hand. If there has been lots of action in all of the previous betting rounds, it's likely that you'll need a very strong hand to call on the river. Players will generally tend not to bluff on the river, especially against several opponents. Therefore, if a player bets against several others when there are draws on the board, that player will usually be holding a good hand.
Betting or raising when you have a strong hand
Most players bet, raise or check-raise on the river when they believe they have the best hand. It's usually the correct move, but doesn't always make sense. Sometimes it isn't enough just to have the best hand - you also want your opponents to call. If their hand is only marginal or weak, they are less likely to call, which means that your raise creates no further action. By contrast, if you have a very strong hand, they may re-raise, which is what you want.
Bluffing the river
As mentioned above, it rarely makes sense to bluff on the river against several opponents. It's highly likely that at least one of the players is holding a medium strength hand that gives them good pot odds. Generally, players will not tend to fold on the river if they have stayed in the hand this long, with the exception of those that miss their draws. You must be extremely careful about the kind of player you try to bluff on the river. The player must be the type that is capable of folding marginal hands on the river - something which many inexperienced players may not be.
As you can see, play on the river differs significantly from other betting rounds. The key is to avoid folding the best hand. But if you are sure that you don't have the best hand, then folding is the right decision. You should only bet or raise if you still feel you have the best hand if your opponent makes the call. Bluffing rarely makes sense either, especially against several opponents, as the probability that at least one of them will call is too high.